You roll a die, winning nothing if the number of spots is odd, $1 for a 2

Question:

You roll a die, winning nothing if the number of spots is odd, $1 for a 2 or a 4, and $10 for a 6.
a) Find the expected value and standard deviation of your prospective winnings.
b) You play twice. Find the mean and standard deviation of your total winnings.
c) You play 40 times. What's the probability that you win at least $100?